Comparison of antioxidant activity of hydroethanolic fresh and aged garlic extracts and their effects on cerebral ischemia.

Antioxidant properties and protective effect of aged garlic extract (AGE) and of 20% hydroethanolic fresh extracts from garlic clove (GCE) and skin (GSE) on cerebral ischemia were evaluated by administering extracts at the beginning of reperfusion in a rat model of stroke. All three extracts scavenged superoxide anion, peroxynitrite anion, and peroxyl radicals, but with different efficiencies; furthermore, GCE and GSE scavenged hydroxyl radicals and GSE scavenged singlet oxygen. These extracts significantly prevented reduction of neuronal nuclear antigen in the infarcted area, although no improvement in neurological function was observed. Importantly, GCE and GSE contained S-allylcystein, a compound associated with AGE's neuroprotective effect against damage induced by cerebral ischemia. Extracts decreased mRNA expression of NR1- and NR2B-NMDA-receptor subunits and prevented ischemia-induced reduction in mitochondrial potential and in ATP synthesis. These results indicate that antioxidants present in garlic extracts may regulate ROS concentrations during ischemia, favour pro-survival pathways, and attenuate mitochondrial dysfunction.